In vivo responses of alloreactive lymphocytes stimulated in vitro. Skin graft rejection mediated by MLR-Primed lymphocytes

Multiple pathways of T-T interaction in the generation of cytotoxic T lymphocytes to alloantigens

The interaction of T helper (Th) cells with syngeneic and allogeneic cytotoxic T lymphocyte precursors (CTL.P) has been investigated. Unprimed and mixed lymphocyte culture-primed peripheral T cells were used as a source of Th. Thymocytes, which depend upon exogenous Th cells for activation, were used as a source of cytotoxic precursors. Data is presented that demonstrates that at least two pathways of T-T interaction can lead to the activation of cytotoxic lymphocytes. The first is an allogeneic effect, in which Th cells recognize and respond to alloantigens expressed on CTL.P. The second is the interaction of Th cells with syngeneic CTL.P, in which both cell types are thought to respond to alloantigens on stimulator cells. The latter interaction can be shown to be restricted by H-2-linked determinants when primed Th cells are used and allogeneic effects against thymocytes are minimized. Restricted interactions between unprimed Th cells and thymocyte CTL.P have never been observed. Mechanisms that may explain the difference between the interaction of unprimed and primed Th cells with CTL.P are discussed.

Uncovered skin grafts in mice

A technique for suturing ear skin on the lateral thoracic area of recipient mice is described. Using this technique the graft was visible from the day of grafting until rejection was complete and mice were not burdened by circumferential body dressings. Consistent mean survival times were observed in a donor-recipient combination over 1 year's time and technical failures could be recognized. This technique was useful to accurately assess accelerated rejection responses in normal mice that occur 4-8 days after grafting as a result of passively transferred effector cells.